Much has been written about the apparent fine tuning of Nature that has enabled our world to form and to initiate and sustain life. An "Anthropic Principle" was first suggested by Brandon Carter at a meeting in Princeton in 1970. The discovery of an unknown energy level in carbon in 1953, after it was predicted by Hoyle, is often cited as the first example of a prediction based on the Anthropic Principle, despite the prediction preceding the formulation of this principle. If it were not for the existence of this energy level (the Hoyle state) there would be no elements beyond boron. No carbon - no life - nothing.
I would like to propose that it is more than a propitious coincidence that those elements at the peak of the binding energy per nucleon curve, namely iron and nickel, also possess the property we call ferromagnetism. Nuclear fusion stops at iron and nickel with iron becoming the most abundant metal in the cosmos. I believe that ferromagnetism played a pivotal role in the formation of our solar system with its planets. Earth's iron/nickel geodynamo ensures a relatively benign environment for life to form and evolve. Without protection from the atmosphere-stripping effect of the Sun's radiation, Earth would probably be as barren as Mars is today. We need iron in our blood to absorb oxygen from the air and plants too need iron to respire and photosynthesise. Iron is surely king!
What is Cosmogony?
The Merriam-Webster dictionary gives two (very similar) definitions.
1: a theory of the origin of the universe
2: the creation or origin of the world or universe
I do not believe that all we can see with with our best telescopes, ground or space based, was created in one 'Big Bang' some fourteen billion years ago. It does not sound plausible to me and there is the unanswered question of what happened to the anti-matter that was supposed to have been created in this Big Bang.
The claim that the cosmic microwave background radiation is a relic of the Big Bang that proves the case for the Big Bang is just as presumptuous in my view as the claim that galactic flat rotation velocity is proof of the existence of 'Dark Matter'. Could the 2.73K blackbody background radiation simply be due to the thermalisation of stellar radiation? Have the proponents of Dark Matter considered the influence of the the billion or so neutron stars that NASA estimate should exist in our galaxy?
I have in mind a scenario I hope to develop for the origin of the universe that does not involve a single big bang event.
What is gravity?
Gravity is the weakest, yet arguably the most dominant force in the universe, but it remains an enigma. Does anti-matter exhibit attractive or repulsive gravity? Perhaps one day the secrets of gravity will be unlocked and then we might really have a 'Theory of Everything'. If we understood why and could prove that gravitational and inertial masses of ordinary matter are equivalent, it might help the cause.
Fundamental Particles
Not so long ago it was thought that there were three fundamental atomic particles - the neutron, the proton and the electron. It turns out that an unbound neutron decays into a proton and electron in about fourteen minutes. Then along came the idea of quarks which exist in triplets to form neutrons and protons, collectively called nucleons. These quarks cannot exist as separate entities outside nucleons. It is accepted that these quarks possess a charge equal to one third of that of an electron or two thirds of that of the positron. It seems to me therefore that the electron or positron cannot be a fundamental particles but must be made of three particles, which I will call the electrino, the little electron. Quarks possess one or two of these hypothesised electrinos, depending on the type of quark, and like the quark the electrino cannot exist as a separate entity outside a nucleon. Outside nucleons, three electrinos form a seemingly indivisible electron.
Evolution of the Solar System
The starting position is taken as the point when the embryonic solar system has a clearly recognisable circumstellar disc with a glowing nucleus or nebula - a protoplanetary disc such as HL Tauri. It is noticeable, even at 1 million years or less, that there are two clearly defined depleted rings. The image of HL Tauri from ALMA presented below has been generated from a new analysis by Japanese scientists of the public data in 2017. Red is dust and blue is the formyl radical HCO-. One interpretation is that planetary formation is underway in these two rings. I think a Jupiter style planet could be forming in the outer ring. A large planet forming early could be crucial in transferring angular momentum from the nebula to the disc, as discussed below.
Hoyle, in his book "The Cosmogony of the Solar System", calculated that the Sun would reach rotational instability by the time it had condensed to a size of 40% of Mercury's present-day orbit if it did not shed angular momentum. It was therefore imperative that angular momentum from our collapsing nebula should be transferred to the circumstellar disc if the process of collapse was to proceed without disintegration. Hoyle favored magnetic coupling between the rotating nebula and the disc to transfer momentum. I think the most plausible mechanism is that of coupling by magnetic/electromagnetic means. A means by which iron/nickel particles became melted or sintered together could be by the generation of eddy currents in the particles, much in the manner of a high-frequency induction furnace.
The rotational velocity of the nebula may be expressed as the equatorial velocity at the surface or as an averaged velocity component of the angular momentum or the rotational kinetic energy of the nebula. I think the transfer of angular momentum from the nebular to the circumstellar disc is most easily understood by looking at the kinetic energy of the system. The magnetic/electromagnetic coupling of the disc and nebula may be thought as acting as a torque converter. The work done by this torque converter can be considered as extracting energy from the nebula and transferring it to the disk. It appears counter-intuitive, but as energy is transferred to the iron-containing components of the rings, these components will be forced to take up a higher radius of rotation, but at a slower orbital or angular velocity. Assuming a circular orbit, moment of inertia (I) varies directly as the square of the orbital radius while the angular velocity (ω) varies inversely as the square root of the radius, hence there is a net gain in angular momentum (Iω) in the disc, neglecting any mass effect.
As angular momentum is transferred by magnetic/electromagnetic coupling, the rotating nebula further collapses while the circumstellar disc expands. The way bands or rings form in the disc is a subject of interest. My instinct tells me that that the nebula could be generating regular and intense vibrational waves as it collapses producing a radial standing-wave-like pattern in the circumstellar disc. The frequency of vibration, along, with other factors, would determine the number of nodes and anti-nodes and hence how many rings are created, which in turn would determine the potential number of planets that could be formed. In the rings a bright central area , darkening towards the edges, can be seen especially in the outer rings of the HL Tauri image on the home page, perhaps giving credence to this interpretation. This could have been an ideal environment for the process of planetary formation with a high concentration of particles in the center of the ring.
Iron/nickel-rich accreted masses, be they large or be they small, as they are driven by the magnetic torque converter to a wider orbit will tend to collide with iron/nickel-poor accreted masses that are no so well driven. Some of the combined kinetic energy of the colliding bodies in the collision will be dissipated as heat. The effect of these collisions will be to bring the combined mass back to a lower orbit.
Therefore, a body that accretes will not move to such a such a high orbit as a body that does not accrete, if both are being driven by the magnetic torque. This raises the possibility that a body, when it reaches the edge of a ring and is still under torque, will be able to migrate out of its parent circumstellar ring into the next one. Imagine a body like this and let us call it Jupiter Junior, still in an Earth like form but possibly larger. Suppose too that there has been little major accretion in this adjacent disc because of slightly less favorable conditions and suppose this disc is in the region where what we call the asteroid belt would have been. Jupiter Junior, still under torque, would be able to work its way through this ring, accreting smaller bodies mainly by gravity, and impacting on larger bodies like wrecking ball. Most of the debris would be accreted into the body of Jupiter Junior, gaining tens of earth-masses in the process. The remainder would be either ejected from orbit or remain in orbit.
Thus Jupiter Junior worked its way through what is now the asteroid belt, leaving a trail of destruction behind. The asteroid Psyche, a large ball of nickel/iron which could be the remnant of an embryonic planet, may be the result of such an impact. It is also likely Junior Jupiter picked up the Trojan asteroids in its Lagrange points on its journey through what is now known as the asteroid belt. Also it is probable that the many very small moons that Jupiter has acquired were captured on this journey.
Migrating outwards under torque, which would likely be increased by a geodynamo in its core, Jupiter Junior would enter the next ring, still a rocky planet, where accretion to moon-sized planetesimals had already occurred. Four of these planetesimals, known today as the Galilean moons, would be captured by a growing Jupiter Junior as it gravitationally attracted hydrogen, helium and rocky material from the cold environment. Undoubtedly some planetesimals would be absorbed by direct impact with this growing planet with a substantial atmosphere of hydrogen and helium. The Galilean moons would be captured by atmospheric retardation rather than direct impact. Jupiter Junior was on the way to becoming Jupiter Senior, the Jupiter we know today and slowed its outward journey as the nebula's angular momentum was transferred not only to Jupiter but the rest of the outer planets.
The Lagrange points L4 and L5 were expected to remain sufficiently stable for the Trojans to remain in place while Jupiter acquired its mass of hydrogen and helium. The coriolis force at these Lagrange points gave the captured bodies self-regulating stability.
This scenario implies that Jupiter Junior began its life in the ring in which Mars originated. It is not an impossible hypothesis if one accepts that Earth and its moon or its moon progenitor shared the same ring during their formation. In the former case the larger body escapes the ring and in the second Earth 'captures' the moon. Perhaps the relatively small size of Mars is due to most of the material in the Mars ring being accreted into Jupiter Junior.
A large planet forming early is considered to be crucial in absorbing angular momentum from the nebula as previously mentioned. Imagine there to be a 'Goldilocks' zone where there is optimum magnetic interaction between the nebula's magnetic field, the concentration of iron/nickel rich agglomerates and the temperature in the disc. In the above scenario this would be the Mars and asteroid rings.
At each stage, as the nebula's rotation slowed and the disk cooled and expanded, the 'Goldilocks' zone would have likely shifted towards the center. This view is supported by studies involving radio-isotope 182Hafnium eventually decaying to 182Tungsten that strongly suggest Mars formed before Earth.
Jupiter's intense magnetic field is claimed, I believe, to be generated in the liquid metallic hydrogen outer core. This may be true, but it may also be the case that the excitation for this 'hydrogen dynamo' comes from a large earth-like geodynamo at the center.
The only external physical evidence we have that may point our thoughts in the direction of how Earth formed are meteorites, primarily from the asteroid belt. Much can be learned from the study and analysis of meteorites, some of which are known to have originated from Mars. There are many classes of meteorites but the one that is of most relevance in this context are the chondrites. They are unmelted, but not necessarily unheated, and are thought to be representative of the building blocks of our planet. Many contain iron and nickel but, as far as I can ascertain, generally not in a sufficient quantity that would give the proportion of metal that we see in Earth's core. The evidence that chondrules experienced a temperature that lead to melting suggests to me that the center of the solar nebular, when it underwent the first stage of nuclear fusion, created such a shock wave that the hot outer layer of the solar nebula was expelled through the circumstellar disc. A short but violent event that left its mark.
It is unlikely we will ever see direct evidence of the nature of the first accretions that became the center of the Earth's core but I would like to propose that it could have been similar to some of the more metallic chondrites but with a higher metal content. If there is anything in my hypothesis that ferromagnetism played a pivotal role in the cosmogony of the Solar System, then I would expect the first accretions to be high in metallic iron nickel and later ones to be low.
Iron is quoted as composing 85% of the body of Mercury. This high figure is often cited as being due to outer rocky layers being stripped off by radiation proximity effects from the sun. I would like to propose that a proximity effect which might directly account for that the high iron content is the strong magnetic influence from the sun or proto-sun, enabling iron-rich accretions to readily form.
The composition of the earth seems to around 35% by weight iron + nickel. Taking a linear rate of diminution with time of metal content of chondritic material incorporated into our planet, implies that there could have been a reduction from an initial 70% to a final zero. I am not sure if the 35% figure I read includes the non-metallic (oxides) iron, which could add another 10% to the total.
I have a picture in my mind's eye of molten rock rising up from a molten iron/nickel rich core rather than molten metal trickling down. We may never know but perhaps in ten year's time we may have filled in some of the gaps in our knowledge following a successful NASA-funded Psyche mission to the asteroid belt to examine what is thought to be a proto-planetary core.
